Synthetic tone generator system

ABSTRACT

The audio signal generated by a missile electronic subsection is passed through a threshold detector and into a gate circuit. Output from the memory circuit causes a tone switch to connect a fire tone generator to the gunner&#39;&#39;s earphone. The fire tone generator produces an audio signal of different frequency and amplitude from that of the &#39;&#39;&#39;&#39;no fire&#39;&#39;&#39;&#39; tone generator.

I United States Patent 1151 3,643,028 Cleveland Feb. 15, 1972 [54]SYNTHETIC TONE GENERATOR 3,015,297 l/1962 Supemaw ..340/148 SYSTEM3,066,633 12/1962 Harry ..1 14/23 2,345,472 3/1944 Goldsmith ..179 I SS[72] inventor: William C. Cleveland, Santa Ana, Calif. v l 731 Assignee:The United sum of America as 'r 'v W Clafiy "pruned by he s f NavyAssistant Examiner-Horst F. Brauner Attorney-R. S. Sciascia and Thomas0. Watson, Jr. [22] F1led: July 9, 1970 21 App]. No; 53,360 1 ABSTRACTThe audio signal generated by a missile electronic subsection 52] us.c1. ..119/1 R, 181/.5 R, 181/.5 51-1 is Passed throush'a thresholddetecmrand into s circuit '5 [BL 041, 13 00 Output from the memorycircuit causes a tone switch to con- [58 fieldofSearch ..179/1 R, 1 ss,1 sw, 1 vc; met fire tone generator to the s earphone The fire 340/27,148; 325/436; 331/153; 102/702; 181/5 tone generator produces an audiosignal of different frequency and amplitude from that of the no fire"tone generator. 6 f t [5] ReereneesCied 0 ,lnrawing UNITED STATESPATENTS 31286931 3 9. GSSF'S 22 "$0512 seusnaron 2a 2a 4 GATE HOLD rmsINHIBIT INDICATOR CIRCUIT SIGNAL 3o Z1o l2 /4 /6 /a 20 GATE MISSILECIRCUIT 8:3 :51 AMPL'F'ER EGAURNPNHEQRNSE AUDIO TONE FIRE TONE ssuennonPNENIEDFEB 15 1912 mozmmzwo mzok EI TTRNEY AGENT INVENTOR. C CLEVELANDmama Mum.

SYNTHETIC TONE GENERATOR SYSTEM STATEMENT OF GOVERNMENT INTEREST Theinvention described herein may be manufactured and used by or for thegovernment of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The present invention relates to a synthetictone generator system and more particularly to a synthetic tonegenerator system which provides an improved firing tone to a gunner whenaiming and firing a missile.

In present day warfare the use of self-propelled missiles and rocketsoff an ever increasingly important role. Due to their adaptability andlong range these missiles are far more effective than any of theprevious ballistic projectiles. In adopting a missile to an everchanging environment there frequency occurs the situation wherein themissile is carried aloft in a bomber type aircraft, and then laterreleased to become an air-to-air or an air-to-surface missile. Sincethese devices are self-propelled there naturally arise problems inhaving them effectively hit a distant target because once the missilehas been launched, then personnel aboard the aircraft which has launchedthis missile has no further control over it. Naturally, many systemshave been devised for the accurate aiming and launching of thesemissiles, and broadly speaking, most of these systems utilize the radaror other direction seeking means located within the missile itself toaim the missile rather than using any direction finding equipment aboardthe aircraft. A signal tone generated by the electronic subsection onthe missile is relayed to the aircraft and the bombardier and navigatoron the aircraft then maneuvers the plane until the missile is accuratelypointed towards the desired target, at which time the missile isreleased.

While these systems for aiming, arming and releasing a missile from anaircraft are effective, they still nevertheless have a number ofdrawbacks in that frequently the audible tone from the missilefluctuates and varies in amplitude due to the fact that the target maymomentarily move out of range of view, or if the missile itself has aheat seeking device in its nose, then there can be distracting sourcesof heat other then the target.

The present invention eliminates a number of these shortcomings andweaknesses in prior art systems in that is provides the followingadvantages:

1. No signal is present duringbore sight tracking.

2. There is no unambiguous fire tone present throughout the total fieldof view when the missile is detecting a target.

3. It eliminates signal level fluctuations due to rapid target aspectangle changes, scintillation, and background hot spots by means ofmemory feature.

4. Provides for aural indication of hold fire function.

5. Provides a monitoring tone indicating proper circuit operation in theabsence of firing tone.

SUMMARY OF THE INVENTION A tone generator comprising a circuit forcomparing a signal generated by a missile subsection with a presentlevel in a threshold detector and when the threshold is exceeded, activating a gate circuit which causes the generating circuit to producean output so long as the missile audio exceeds the threshold unlessinhibited by a hold fire signal indicator signal.

OBJECTS OF THE INVENTION An object of the present invention is theprovision of an improved firing tone for a missile gunner.

Another object of the present invention is the provision of a tonegenerator system in which no signal null is present during bore sighttracking.

Still another object to the present invention is the provision of afiring tone system which has no unambiguous fire tone throughout thetotal field of view when the missile is detecting a target.

Yet another object of the present invention is the provision of a firingtone system which eliminates signal level fluctuations due to rapidtarget aspect angle changes, scintillation, and background hot spots.

Yet another object of the present invention is the provision of a firingtone for aural indication of hold fire function.

Still another object of the present invention is the provision of afiring tone system which provides a monitoring tone indicating propercircuit operation in the absence of firing tone.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings in which like referencenumerals designate like parts throughout the figures thereof andwherein:

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTReferring now to the lone figure there is shown an input terminal 10 towhich is supplied to the audio signal as generated by the missileelectronic subsection (not shown The signal from input terminal 10 isapplied to a threshold detector 12 and from thence to a gate circuit 14.Gate, circuit 14 functions to operate a tone switch 16 whose output isapplied .to an amplifier 18 which in turn is connected to a gunnersearphone 20. Connected so as to apply another input to the tone switch16 is a no fire tone generator 22, which is one of two indicator tonegenerators. A fire tone generator 24, which is the other indicator tonegenerator, supplies to a third input to the tone switch 16.

A second input terminal 26 is used to receive a hold fire indicatorsignal as produced by other fire control equipment (not shown).Connected to input terminal 26 there is a gate inhibit circuit 28, theoutput of which is used as a second input to inhibit gate circuit 14. Alead 30 which is connected at one end to input terminal 10 is connectedat its other end to gate inhibit circuit 28 so as to provide the missileaudio tone as a second input tocomponent 28.

Turning now to the operation of the invention it can be seen that audiosignals generated by the missile electronic subsection are applied toinput terminal 10 where it is compared to a presetlevel in the thresholddetector 12. Whenever the target signal-to-noise level exceeds thispreset level, a gate circuit 14 is activated. This circuit produces anoutput as long as the missile audio level is above this threshold levelindependent of amplitude nulls in the missile audio due to radicaldesign characteristics, and so long as the target is within the anglefield of view of the seeker.

Output from the gate, circuit 14 causes the tone switch 16 to connectthe fire tone generator 24 to an amplifier 18. The output of amplifier18, whose gain is adjustable, then is connected to the gunners earphoneor audio device 20. The fire tone generator 24 produces an audio signalof different frequency and amplitude than that of the no fire tonegenerator 22 which is also connected to the tone switch 16.

If the gate circuit output from 14 is zero for any reason, such asamplitude is below the threshold, or target is out of the field of view,or the hold fire indicator signal is present on input 26, the toneswitch 16 connects the no fire tone generator 22 to the amplifier 18 andgunners earphone 20. This tone, as-noted previously, is of a markedlydifferent (lower) amplitude and frequency than that of the fire tone 24so that the gunner will have no difficulty in distinguishing between thetwo indicator tones. It can been seen that if there is a signal on thehold fire input terminal 26 which in turn activates gate inhibit circuit28, this functions to stop any output from gate circuit 14, deenergizingtone switch 16 and applying no fire tone generator 22 as describedabove.

From the above description of the structure and operation of theinvention it is clear that there is presented herein a synthetic tonegenerator system which provides many improvements and advantages overprior systems. Here, a reliable audio signal is provided to the pilotand gunner as a firing tone and one which is not subject to signal levelfluctuations due to target change for angle, scintillation or backgroundhot spots. Also the elimination of ambiguous fire tone signalsthroughout the total field of view when the missile is detecting atarget is a desirable and sought for end in the field of fire control.

Obviously many modifications and variations of the present invention arepossible light of the above teachings. ls therefore to be understood,that within the scope of the appended claims, the invention may bepracticed otherwise than as specifically described.

I claim:

1. A synthetic tone generator for use in a missile fire control systemcomprising:

means for receiving an audio tone from the missile subsection;

second means connected to the receiving means to be activated if theaudio tone has reached a preset level;

a gate circuit connected to the second means;

a switch operable by the output of said gate circuit; indicator tonegenerator connected to an input of said switch; an amplifier connectedto the output of the switch; and audio means connected to the amplifierfor rendering the indicator tone audible to a gunner.

2. The device of claim 1 wherein the second means is a thresholddetector.

3. The device of claim 2 wherein the switch is a tone switch.

4. The device of claim 3 wherein the indicator tone generator includes anofire tone generator connected to the tone switch.

5. The device of claim 4 wherein the indicator tone generator alsoincludes a fire tone generator connected to the tone switch.

6. The device of claim 5 further including means for receiving hold firesignals;

a gate inhibit circuit connected to receive the hold fire signals;

means connecting the audio tone from the missile subsection to said gateinhibit circuit; and

means connecting the output of said gate inhibit circuit to said gatecircuit;

whereby upon receipt of a hold fire signal said gate inhibit circuitprevents said gate circuit from producing an output in response to asignal from said threshold detector.

7. The device of claim 6 wherein the fire tone generator produces anaudio signal of different frequency and amplitude than that of theno-fire tone generator.

8. The device of claim 7 wherein the gate circuit produces an output solong as the missile audio level is above the threshold detector levelindependent of amplitude nulls in the missile audio due to reticledesign characteristics.

9. The device of claim 8 wherein the gate circuit produces an output solong as the target is within the angular field of view of the seeker.

10. The device of claim 9 wherein if the gate circuit output is zero thetone switch connects the no-fire tone generator to the amplifier andgunner's audio means.

1. A synthetic tone generator for use in a missile fire control systemcomprising: means for receiving an audio tone from the missilesubsection; second means connected to the receiving means to beactivated if the audio tone has reached a preset level; a gate circuitconnected to the second means; a switch operable by the output of saidgate circuit; indicator tone generator connected to an input of saidswitch; an amplifier connected to the output of the switch; and audiomeans connected to the amplifier for rendering the indicator toneaudible to a gunner.
 2. The device of claim 1 wherein the second meansis a threshold detector.
 3. The device of claim 2 wherein the switch isa tone switch.
 4. The device of claim 3 wherein the indicator tonegenerator includes a nofire tone generator connected to the tone switch.5. The device of claim 4 wherein the indicator tone generator alsoincludes a fire tone generator connected to the tone switch.
 6. Thedevice of claim 5 further including means for receiving hold firesignals; a gate inhibit circuit connected to receive the hold firesignals; means connecting the audio tone from the missile subsection tosaid gate inhibit circuit; and means connecting the output of said gateinhibit circuit to said gate circuit; whereby upon receipt of a holdfire signal said gate inhibit circuit prevents said gate circuit fromproducing an output in response to a signal from said thresholddetector.
 7. The device of claim 6 wherein the fire tone generatorproduces an audio signal of different frequency and amplitude than thatof the no-fire tone generator.
 8. The device of claim 7 wherein the gatecircuit produces an output so long as the missile audio level is abovethe threshold detector level independent of amplitude nulls in themissile audio due to reticle design characteristics.
 9. The device ofclaim 8 wherein the gate circuit produces an output so long as thetarget is within the angular field of view of the seeker.
 10. The deviceof claim 9 wherein if the gate circuit output is zero the tone switchconnects the no-fire tone generator to the amplifier and gunner''s audiomeans.